A nonspecific fatty acid within the bumblebee mating plug prevents femalesfrom remating

The best mating strategy for males differs from that of females, because fe males gain from mating with several males (polyandry), but males gain from monopolizing the females, As a consequence, males have evolved a variety of methods, such as the transfer of inhibitory substances from their accessor y glands, to ensure exclusive paternity of the female's offspring, generall y with detrimental effects on female fitness. Inhibitory substances have be en identified as peptides or other specific molecules. Unfortunately, in so cial insects male-mating traits are investigated only poorly, although male social insects might have the same fundamental influence on female-mating behavior as found in other species. A recently developed technique for the artificial insemination of bumblebee queens allowed us to investigate which chemical compound in the mating plug of male bumblebees, Bombus terrestris L., prevents females (queens) from further mating. Surprisingly, we found that the active substance is linoleic acid, a ubiquitous and rather unspeci fic fatty acid. Contrary to mating plugs in other insect species, the bumbl ebee mating plug is highly efficient and allows the males to determine quee n-mating frequencies.